Anybody got any personal ideas for Shadow Absalom Station? I find that place pretty interesting.
I used the Shadow Plane pretty extensively in my current campaign. The way it tended to work -- it wasn't a true inversion of the Prime Material but it often worked as a mirror image -- was that locations that were full of life and bustle in our plane were often dead and half-destroyed on the Shadow Plane, inhabited only by shadow creatures of negative energy. By contrast, sometimes there were locales that seemed dead and ruined on the Prime Material that were still active and full of some kind of "life" on the Shadow Plane.
I never got to do a Shadow Plane version of Absalom Station, although I planned for the possibility: the adventure just didn't move that way. If I'd gotten to do it, though, the Shadow Plane version of Absalom Station would have been abandoned and half-wrecked, warped and weird, portions of it open to the void and the remainder overrun by various creatures of Shadow, with a very few Kayal-type humanoids forming expeditions and bridgeheads. So, that's one possible way to go.
The Shadow Plane was serving a very specific plot function in my adventure, though. If I were doing the scenario in isolation I might take it further over-the-top and deeper into horror territory and have the station overrun by Kytons and their minions.